For a typical camera and endoscope assembly as used in minimally invasive surgery (MIS), the camera is connected to a coupler, which, in turn, is connected to the eyepiece of a rigid endoscope. The use of drapes provides a solution to the well-known problem of sterility in the operating room. When drapes are used, the camera and coupler are non-sterile, while the endoscope is sterile. A tubular plastic drape is positioned around the camera and coupler in order that they may be used within the sterile field around the operating table. Frequently, they are laying on the patient.
Using a conventional drape, at the start of the MIS procedure, a nurse pushes the eyepiece of the endoscope through a small elastic hole in the camera drape, and attaches the endoscope to the coupler and camera. Once this step is performed, the MIS procedure may continue. However, the eyepiece of the scope is now considered non-sterile, and may not be removed from the drape during the remainder of the procedure. If the physician wishes to change the endoscope or refocus the camera coupler during the procedure, the nurse must typically struggle with the manipulation of complex mechanical and optical parts located within the plastic drape.
Another conventional approach is to put a transparent optical grade window in the drape, so that the camera remains inside the drape, and the endoscope remains outside the drape. In most instances, the window is of necessity a lens because its existence changes the focal length of the optical train. Such a lens is expensive, but the lack of a lens often provides unwanted magnification at the camera and unwanted reduction in field of view. Further, camera drapes are typically single use items. Once they are used, they are no longer sterile. The cost of a high quality optical window in a drape that will see use only once is simply too high.
U.S. Pat. No. 5,433,221 to Adair discloses a windowed drape for a surgical camera which includes a cylindrical generally flexible non-elastic body and a flexible elastic end portion having an optically clear window integrally formed with the distal end portion. The surgical camera and coupler are positioned within the drape. The coupler and endoscope connection is made with the window therebetween. As disclosed in the patent, a well known shortcoming in the art includes the lack of high quality optically clear material for the windows.